Sleeping Giants by Sylvain Neuvel

If you loved The Passage, World War Z, The Martian or Interstellar: this is a must-read thriller for you.

* * *

Deadwood, USA. A girl sneaks out just before dark to ride her new bike. Suddenly, the ground disappears beneath her. Waking up at the bottom of a deep pit, she sees an emergency rescue team above her. The people looking down see something far stranger...